How do you go round sovling this one

Question

43₅ - 34₅ =

Answer 1

There are at least two different methods for solving this 3-digit subtraction problem. Common core uses a place value chart; with a hundreds place, a tens place, and a ones place. On the chart, either place tally marks or circles to represent each digit of the first/largest number of the subtraction equation in each place value space. There will be 4 circles in the hundreds, 3 circles in the tens, and 5 circles in the ones. Next we will begin taking away the number of circles in each place value, starting with the ones. There are 5 ones to take away, and 5 ones available to take from, so we will cross out all 5 in the ones place. 5 ones - 5 ones = 0 ones.

There are only 3 tens available to take from, but we need to subtract 4; so we will turn one of the hundreds into 10 tens in order to have enough to subtract. Cross out one of the hundreds circles, and draw 10 circles in the tens place under the 3 circles that are there. Now we can cross out 4 of the 13 circles in the tens place, leaving 9 circles. 13 tens - 4 tens = 9 tens.

Last we will take away 3 hundreds circles from the 3 hundreds that are still there after borrowing one of them for the tens. 3 hundreds - 3 hundreds = 0 hundreds

We now have 0 hundreds, 9 tens, and 0 ones; so 435 - 345 = 90.

The next method is more traditional, placing the numbers vertically with each place value lined up with the other.

435.

-345

______

0 9 0

There are 5 ones available and we need to take 5 away, so there are 0 ones left. Cross out the 3 tens since we cannot take away 4 tens from only 3. We have to borrow from the hundreds. There are 10 tens in one hundred, so cross out the 4 in the hundreds place and you write 3 above it since there are only 3 hundreds there now. Add the 10 tens to the 3 tens there and write 13 above the 3. 13 is more than 4; when we take away the 4 tens there are 9 tens left over. In the hundreds place there are 3 available and we need to take 3 away, so there are 0 hundreds left. That leaves 0 hundreds, 9 tens, and 0 ones, so 435 - 345 = 90.