Expert: Lynn Houston - 9/9/2008

Question
My son is in the 5th grade and their math is sort of different than when I was in school. the question says" What is the greatest number of times you would regroup when multiplying a 3-digit factor by a 2-digit factor? Can you explain?
thanks

Answer
Ok, had to look around a little, but basically, what it means is how many times the product carries.

 999
 x99
=====
 991 (9x9, carry the 8 (1), 9x9, carry the 8(2)
991  (9x9, carry the 8 (3), 9x9, carry the 8(4)
=====

Since 999 and 99 are the largest 3 and 2 digit numbers you can have, 4 is the maximum of times you would have to regroup.

Btw, apparently you can also have regrouping in addition, subtraction and division and you're right, it sure has changed since I was a kid.