Math Trick for Fast Multiplication

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  • čas přidán 8. 09. 2024
  • #fastmathtricks
    #mentalmath
    #mathtrick This math trick is pretty easy to do, and can be done in your head faster than a calculator.
    This trick only works when multiplying numbers that both end in five. A couple of simple steps and you're done!
    In addition, the mathematical reasons why this trick work are simply explained at the end of the video.
    To support tecmath on Patreon: / tecmath To donate to the tecmath channel: paypal.me/tecm... To donate to the tecmath channel: paypal.me/tecm...
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Komentáře • 97

  • @benthomas6359
    @benthomas6359 Před 5 lety +27

    I’m so happy you started uploading again! My GCSEs started this year and these videos are a massive help

  • @mikoajpasnikowski7522
    @mikoajpasnikowski7522 Před 5 lety +14

    I love this trick! It's so simple and easy to remember + the fact that it works with numbers with 3-digit numbers as well as 2-digit is really helpful. Keep up the good work and thanks for all the help on your channel!

  • @sid6784
    @sid6784 Před 5 lety +13

    Another way of selecting an answer in multiple choice questions is-
    Question: multiply 10x+5 and 10y+5
    Steps- Add X+Y...(a) if answer is even then our eventual answer to (10x+5)(10y+5) will have 25 at the end...(b) if the answer is odd then our eventual answer will be 75
    This way people can eliminate answer choices and select the answer wisely in shortage of time

    • @karinisvetcool
      @karinisvetcool Před 5 lety +1

      I've never understood multiple choice math or calculus tests.

  • @spicychipeater761
    @spicychipeater761 Před 5 lety +8

    Thank for all you done you helped me through 4rth to 5th grade thank you for everything

  • @sharonjuniorchess
    @sharonjuniorchess Před 4 lety +2

    I liked the explanation at the end but a visual representation may help people to see what the algebra is actually. doing A rectangle of 35 on one side and 65 on the other can be reduced to a rectangle of 30 x 60 with a band of 5 surrounding it. This band consists of two rectangles (5 x 30 and 5 x 60) plus one square in the far corner (5 x 5). So the total sum/area is:
    (30 x 60) + ((30 + 60) x 5) + (5 x 5) = 1800 + (90 x 5) + 25 = 1800 + 450 + 25 = 2275.
    It was looking at problems like this that helped the arabs to derive algebra; to describe what they were doing.

  • @MistyyyYT
    @MistyyyYT Před 5 lety +7

    Wow I got a test coming and this is what I get amazing!

  • @hichamelattaoui
    @hichamelattaoui Před 5 lety +5

    Love it,my 10 years and 8 years will love it and they will be showing off at school 😉 like usual.

  • @RoseAngella
    @RoseAngella Před 5 lety +2

    Knowing why it works is a must for me. Thanks for sharing. 💚

  • @seemapatilJapan
    @seemapatilJapan Před 4 lety +1

    very good skills.. thanks

  • @lukedevlin45
    @lukedevlin45 Před 5 lety +47

    It sounds like your voice is in constant slow motion

  • @lidamg4074
    @lidamg4074 Před 5 lety +2

    Thank you

  • @divyoroy9056
    @divyoroy9056 Před 5 lety +2

    Good job

  • @shadmanameen2270
    @shadmanameen2270 Před 5 lety +2

    Loved the trick

  • @Rayhid1956
    @Rayhid1956 Před 5 lety +1

    Very good.

  • @lavenderlady9942
    @lavenderlady9942 Před 5 lety +2

    👏👏👏
    Big thanks to you

  • @fonze5664
    @fonze5664 Před 3 lety

    The math nerd in me is totally amazed and enthralled by this dark magic trick 🤓 I'm going to use this every time I have to multiply two numbers that happen to end in 5 in my everyday lif-- oh wait, now I'm sad.

  • @augustogonzalez6665
    @augustogonzalez6665 Před 5 lety +1

    You teach me a lot thanks

  • @gassics4225
    @gassics4225 Před 5 lety +7

    Failed maths so now im here :(

  • @williambunter3311
    @williambunter3311 Před 4 lety

    A very handy method. The proof is an example of the benefits of playing around with numbers and discovering new truths about arithmetical patterns! I'm sure that when Pythagoras discov
    vered the right angle triangle equation it was as a result of just doodling around with two squares, rather than from an effort to prove an established theorem.

  • @lechaiku
    @lechaiku Před 6 měsíci

    the easier way without multiplying by 100 and avoiding decimals:
    45
    x 95
    -------
    4 x 9 || 5 x 5
    36 || 25
    + 6 5 ----> add the average of 40 + 90 (65) and put just before the unit's place
    ----------------
    = 42 75
    135
    x 85
    -------
    13 x 8 || 5 x 5
    104 || 25
    + 10 5 ----> add the average of 130 + 80 (105) and put just before the unit's place
    ----------------
    = 114 75

  • @zanelemazibuko4972
    @zanelemazibuko4972 Před 4 lety +1

    can you make bodmas ,exponents ,roots ,functions and relations because my son enjoys learning your math tricks and they have helped him improve in maths

  • @sdavies9060
    @sdavies9060 Před 5 lety +2

    Nice

  • @psycod2548
    @psycod2548 Před 5 lety +1

    Mate, thank so much

  • @MrMr-yy5th
    @MrMr-yy5th Před 4 lety +1

    Math trick!!

  • @elizapadua6847
    @elizapadua6847 Před 4 lety +1

    Your a wizard math

  • @katherine101able
    @katherine101able Před 3 lety

    Very lovely

  • @ahnafrahamanchoudhury
    @ahnafrahamanchoudhury Před 4 lety

    I love Maths and Math teachers

  • @josh5784
    @josh5784 Před 4 lety +1

    Yes

  • @kay14042
    @kay14042 Před 5 lety +1

    As always brilliant
    Thanks

  • @fat4ll
    @fat4ll Před 5 lety +1

    There are nice tricks

  • @noelsingh7065
    @noelsingh7065 Před 3 lety

    U r a great math teacher!

  • @aishawaddah5311
    @aishawaddah5311 Před 3 lety

    Tou are the best in the world

  • @phillipcoppernoll2056
    @phillipcoppernoll2056 Před 3 lety

    For the last equation. Just do it like the others. 6x3=18, 6+3=9, Divide by 2= 4.5 .. 18+4.5= 22.5, Then add your 5x5=25 AND the answer is 2275. Right?

  • @videosrus99
    @videosrus99 Před 3 lety

    I must point out that you missed explaining how you arrived at "add 25" in the first problem. Clearly it is 5x5 but you need to explain that and not assume everyone saw that. I actually thought you were going to work out the problem by multiplying 35 x 100 then subtracting 35x5 which is all mental arithmetic. Something my mum taught me about 60 years ago. Not seen your method before and I think it works better than mum's. Very interesting. I am really enjoying your videos. Thank you.

  • @Reachermordacai
    @Reachermordacai Před 5 lety

    Awesome, thanks.

  • @elizapadua6847
    @elizapadua6847 Před 4 lety

    Keep a good work

  • @fieryphoenix897
    @fieryphoenix897 Před 4 lety

    I LOVE THESE

  • @jamiehopkinson1597
    @jamiehopkinson1597 Před 5 lety

    You still upload alot so great

  • @baileyrichardson5145
    @baileyrichardson5145 Před 5 lety +6

    LOVE YOU DAD 💙💙

  • @valor36az
    @valor36az Před 4 lety

    How awesome!

  • @Nick-yv1wy
    @Nick-yv1wy Před 4 lety

    Bro how does anybody dislike this kind of stuff??

  • @sammysidd7806
    @sammysidd7806 Před 5 lety +2

    I learned lots things!

  • @GodIsEverPowerful
    @GodIsEverPowerful Před 5 lety

    pgood. because the no. of multiplications is less! (compared to regular no. of four multiplications) nice

  • @AndrejNikolov-xw2gi
    @AndrejNikolov-xw2gi Před 5 lety +1

    Thank you for coming back!

  • @ericthemadscientist8357
    @ericthemadscientist8357 Před 4 lety +1

    Huh neat

  • @mackymadness86
    @mackymadness86 Před 4 lety

    Love this channel. You sound like a stoned maths teacher but great content

  • @edwardmiddleton1690
    @edwardmiddleton1690 Před 4 lety

    Hey...can you do Constant of Proportionality, please and thank you?

  • @emmaford5618
    @emmaford5618 Před 4 lety

    Such a massive help!! Thank you for these step by step guides!

  • @abdulrazack9270
    @abdulrazack9270 Před 3 lety

    ** who expected me being 11th grade student in CBSE was looking for this video

  • @TSSUNIX12
    @TSSUNIX12 Před 5 lety +1

    45x95 can you solve using this method

  • @johnryder1713
    @johnryder1713 Před 5 lety

    Well no matter how long it is since you done one of these videos I'll miss em if it was every day

  • @joannehall702
    @joannehall702 Před 5 lety +1

    It would be great if you could add more nursing drug calculation😊

  • @Pablo-dn4to
    @Pablo-dn4to Před 5 lety

    Can us do a video of using a square root in ours calculators please!!!

  • @MrGyges
    @MrGyges Před 5 lety

    You brighten my dimness

  • @johnng1078
    @johnng1078 Před 3 lety

    that's not an aussie accent, that's your voice after eating a meatpie at the AFL

  • @HeavyMetalRuinedMyLife1971a

    The spherical trigonometry calculation for globe earth curvature is 8 inches per mile squared....this is demonstrably non existent 😎

  • @blackbird8010
    @blackbird8010 Před 5 lety +3

    Damn

  • @saiabhi9918
    @saiabhi9918 Před 4 lety +1

    another wrong method by applying i am getng ok try to solve this
    42*43=1806is actual answer but infact iam gettinh 2006

  • @platinumknight1
    @platinumknight1 Před rokem

    man im looking for a trick i knew like i could multiply 6.748.123 times 3.968.436 in under a minute and very easy but i forgot what it was

  • @adrianchineaamoros3230

    Sr your system does not work with 23 x 33

  • @drax6445
    @drax6445 Před 2 lety

    Hi love your classes as it helps me in high school. I am confused with say doing 127 * 86 in my head. So by your trick the first part is 128*8=96 then add (12+8)/2 which I get 106. Then 106*100 + 42 = 10642 but this is wrong. Can please explain. Thank you

    • @itsmemailingyou4234
      @itsmemailingyou4234 Před 2 lety

      It only works if the numbers end in 5 (both being half of ten is why it works).
      10*10=100
      5*10=50
      100/50=2

  • @ahmedaboomer7796
    @ahmedaboomer7796 Před 3 lety

    what does ( Av ) mean

  • @joannehall702
    @joannehall702 Před 5 lety +2

    🥰

  • @lizzeelike
    @lizzeelike Před 4 lety

    why u do average? is this trick work for 45X96?

  • @selmerrasonable2601
    @selmerrasonable2601 Před 2 lety

    35×26

  • @francescovalente7436
    @francescovalente7436 Před 4 lety

    35x95= 35x100 -(5x35) = 3500-175= 3325

  • @ahnafrahamanchoudhury
    @ahnafrahamanchoudhury Před 4 lety

    Opps! is this for 4- 12?

  • @jacobkris4410
    @jacobkris4410 Před 4 lety

    Sounds like the turtle from FInding Nemo.

  • @green_Mascheen
    @green_Mascheen Před 4 lety +1

    35 x 65 =
    3x6 = 18
    Av. (3+6)/2 = 4.5
    18 + 4.5 = 22.5
    22.5 x 100 = 2250
    2250 + 25 = 2275

  • @linlove7929
    @linlove7929 Před 4 lety

    Loved the trick....you lost me with explanation.....sometimes it’s best not to know why! Love your videos....they help me do my grandsons homework. Thankyou

  • @sorankurdi1414
    @sorankurdi1414 Před 4 lety

    85X33=?

  • @MicCheckMemoirs
    @MicCheckMemoirs Před 5 lety

    Dude I could of used this when I was in the third grade :/, I guess better late than never.

  • @hughmacmillan3156
    @hughmacmillan3156 Před rokem

    No answer at the end. 🤦🏼‍♂️

  • @jessesambro9535
    @jessesambro9535 Před 5 lety +1

    ❤️

  • @ItsThatMilkshake
    @ItsThatMilkshake Před 5 lety +2

    Doesnt work with 82x75

  • @TheHdawson
    @TheHdawson Před 3 lety

    I was doing fine until the explanation of why this works- now I'm totally confused with the XY explanation and don't understand. Glad everyone else understands, but, you lost me totally with the XY explanation.

  • @daphnemckayla7676
    @daphnemckayla7676 Před 4 lety

    The trick worked alot but the end of the explanation confused me. I got 99.5% right.

  • @UneekBruh
    @UneekBruh Před 5 lety +2

    Comment🤣

    • @tecmath
      @tecmath  Před 5 lety +1

      Thank you for it!

    • @UneekBruh
      @UneekBruh Před 5 lety

      @@tecmath no worries. Great vid👌

  • @ahnafrahamanchoudhury
    @ahnafrahamanchoudhury Před 4 lety

    class?

  • @kimberlyroute5983
    @kimberlyroute5983 Před 5 lety +4

    You lost me after 3300. I have know ideal how you got 25 Not clear at all.

    • @jsaeong
      @jsaeong Před 5 lety +2

      Kicking it with Kim KIWK the 25 is just the 5x5 in the ones place

    • @christopherwilson6527
      @christopherwilson6527 Před 5 lety +2

      Really? Even though he said where the 25 came from multiple times?