Using this tactic can help you visual subtraction too. Try taking four marbles away from your pile of eight marbles. You’ll end up with four marbles left. That means that eight minus four equals four.
One plus four equals five, so you would write a five below the line you made under those two numbers. Now add the ‘2’ from 21 and the ‘1’ from 14. Two plus one equals three. Write the three under those two numbers to the left of the five that you just wrote. You should have the numbers 3 and 5 sittings next to each other below the line you drew. That means the answer to this problem is 35. 14 + 21 = 35. If you add two numbers together and they make another two digit number, take the one from that two digit number and move it over to the left. For example, if the problem was 14 + 28 instead your first calculation would be 8 + 4. This would give you 12. You would still put the ‘2’ from 12 below the line underneath the 4 and the 8. However, the ‘1’ from 12 would then be moved over to the left and added to the second equation. So you would add the ‘1’ from 14, the ‘2’ from 28 and the ‘1’ from 12. That would give you the number 4 once you add all those numbers together. This means that 14 + 28 must equal 42.
The idea behind division is splitting equal parts into groups. If you have a pizza with eight slices and four friends, how should you split it up so that each person gets an equal amount of the pizza? In division, that problem would be written as eight divided by four. Each person gets two pieces of pizza.
