Video: KS1-M18 • Paper 1 • Question 19

67 + 33 = ＿.

02:31

Video Transcript

67 plus 33 equals what.

We’re given two two-digit numbers. And we need to find the total of them. How much are they worth all together? We can break down or partition both numbers into their tens and ones to help us to add them together. 67 is made up of six tens and seven ones. 60 and seven make 67. We can break down 33 into three tens and three ones. 33 is the same as 30 plus three. So to add these numbers together, we need to work out 60 plus seven plus 30 plus three.

To help us do this, let’s add the ones first and then the tens, first the ones. What’s seven ones add three ones? Well, we can recognize this quickly because seven and three are a pair that make 10. Seven ones plus another three ones equals 10 ones, which is the same as one ten. So by adding the ones together, we get an answer of 10.

Now, let’s add the tens together. What are six tens plus three tens? Six add three is nine. So six tens plus three tens equals nine tens. Remember, we’ve already made one ten already. Six tens plus three tens or 60 plus 30 equals nine tens or 90. And if we add the 10 we already had, we get 10 tens or 100. So if we’re using blocks to model our answer, we can swap 10 tens rods for 100 square.

First, we added the ones. Then, we added the tens. Then, we added both parts together to find the answer. We found that 67 and 33 are a pair of numbers that make 100. So we can use a hundred square to check that our answer is correct.

67 plus 33 equals 100.