A simple algorithm for calculating 99.. 9 (88) x99.9 (88) + 199.9 (88) to solve the problem of grade 4 in primary school

A simple algorithm for calculating 99.. 9 (88) x99.9 (88) + 199.9 (88) to solve the problem of grade 4 in primary school

99.. 9 (88 pieces) x99.9 (88 pieces) + 199.9 (88 pieces) = 99.. 9 (88 pieces) x99.9 (88 pieces) + 99.9 (88 pieces) + 10 ^ 88 = 99.. 9 (88 pieces) x [99.9 (88 pieces) + 1] + 10 ^ 88 = 99.. 9 (88 pieces) x 10 ^ 88 + 10 ^ 88 = 10 ^ 88 x [99.9 (88 pieces) + 1] = 10 ^ 88 X10 ^ 88

8×9=72、88×99=8712、888×999＝887112
Then 88888888 * 9999999 = ()
888…… 8 (100 8) * 999 9 (100 9) = ()

8  9  88  99  008712888  999  8871128888  9999  8887111288888  99999  8888711112888888  999999  8888871111128888888888  99999  88871111112 and so on, the result is that the number of digits in front 8 is * 87 + the number of digits in back 9 is replaced by * 12, and the number of digits in 8 * 8 is 888871111

1、 13 / 12, 26 / 25, 39 / 38, 13 / 10, 26 / 21, 39 / 32

In the first question, 1 is greater than 2 is greater than 3, so is the second question