Use place value to subtract 639 from 737 . How many times do you have to regroup?

To subtract 639 from 737 using place value, start with the ones place. Since 7 is less than 9, you'll need to regroup from the tens place. This means borrowing 1 from the tens place (which was 3, making it 2), turning your 7 ones into 17 ones. Now, you can subtract 9 from 17, which equals 8. Moving on to the tens place, now you have 2 tens left. Since 2 is less than 3, you'll need to regroup from the hundreds place. Borrowing 1 from the hundreds (which becomes 6) turns your 2 tens into 12 tens. Subtracting 3 from 12 gives you 9. Finally, in the hundreds place, you have 6 and need to subtract 6 (since 639 has 6 hundreds), which is 0. Overall, you regrouped twice: once for the ones and once for the tens!