Multiplying together numbers just below 100

To multiply together numbers close to and below 100:   ex.  96 x 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 x 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 x 97 = 9021      94 x 88 = 8272      97 x 97 = 9409

 

To multiply together numbers close to and above 100:    ex. 107 x 102 = 10914

-Follow step one above:    107 – 100 = 7      102 – 100 = 2         7 x 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 x 111 = 12099     103 x 105 = 10815      112 x 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.