To multiply together numbers close to and below 100: ex. 96×98=9408
-Subtract each number being multiplied from 100 and multiply these differences together. This yields the last two digits of the answer. ex. 100-96=4 100-98=2 4×2=_ _ 08
-Add the differences above and subtract from 100. This yields the first 2 digits of the answer. ex. 4+2=6 100-6=94_ _
*An alternate last step: You can take the difference from 100 of one number being multiplied and subtract this from the other number being multiplied (subtract because you are below 100). 96-2 and 98-4 give the same result as 100-(2+4). Either way is fine.
Try these: 93×97=9021 94×88=8272 97×97=9409
To multiply together numbers close to and above 100: ex. 107×102=10914
-Follow step one above: 107-100=7 102-100=2 7×2=_ _ _14
-Begin step two above, adding the differences, but this time add this to 100. This yields the first three numbers of the answer. ex. (7+2)+100=109_ _
Try these: 109×111=12099 103×105=10815 112×112=12544
*An alternate last step: You can take the difference from 100 of one number being multiplied and add it to the other number being multiplied (add because you are above 100). 107+2 and 102+7 give the same result as (7+2)+100. Either way is fine.
Leave a Reply