Which of the following has the same result as 700 add 21? Is it 700 add 20 add one, 700 add 10 add two, 200 add 10 add seven, or 200 add 70 add one?
The question tells us that the hundreds part of our number is 700. So this can’t be the correct answer. It has two hundreds. We also know that this is not equal to 700 add 21 as it has two hundreds.
Next, we need to look at the tens part of the number. 21 has a two in the tens place. Two tens are 20. So this is not equal to 721 because it only has one ten. 700 add 10 add two does not equal 721.
We know our number has a one in the ones digit. So our number is 700 plus 20 plus one. 721 is the same as 700 and 20 and one.