Subtraction Regrouping Across Two Zeros: 3 Digit Numbers
While subtracting from one zero is difficult enough, subtracting from two or more "zeros" is confusing for many students. If your student shows difficulty with this type of problem, download the worksheet and teach this fantastic trick for subtracting with side-by-side zero's (remember, this trick only works if there are multiple zeros to the right of a number (such as 400 below)
STEP 1: Cross out each number
STEP 2: Rename the ones column as a "10"
STEP 3: Rename the all other "0" columns as a "9"
STEP 4: Rename the last whole number one less (in this case rename the "4" as a "3"
STEP 5: Subtract normally
This trick works not only for this problem with two zeros, but also works if you have ten zeros!. You can see how knowing this will make life much easier for our junior math students. It is important to note that this trick works everytime as long as the digits in the ones place in the bottom number is not a "0" (for example, if the "6" below were a "0" the trick would not work. That is the only exception.
What is the correct answer to this subtraction problem with two zeros?