Victoria knows how to use a hundred square to add. “Every time I jump down, I add 10. Every time I jump right, I add one.” How many tens did she add? How many ones did she add? What is the missing number? 34 plus what equals 58?
We know that Victoria is adding together two numbers. And the total of these two numbers is 58. And we know that Victoria is using a hundred square to help her add. She’s placed an orange circle around the number 34 because that’s where she’s going to start counting. Victoria knows that every time you jump down a square on a hundred square, you need to add 10. So, we need to work out how many squares Victoria counted down.
She started at 34 and she counted down one square to get to 44 and she counted down a second square to get to 54. So, Victoria added two tens. And we know that two tens make 20. Victoria says every time she jumps right on the hundred square, she adds one. Let’s count how many times she jumped right. She was on number 54. She jumped right once to 55, twice to 56, three times took her to 57, and four times took her to 58. Victoria counted to the right four times, which means she added four ones.
Now, we just need to work out which number we get if we have 20 plus four or two tens plus four ones. 20 and four is 24. So, the two numbers that Victoria was adding are 34 and 24. 34 and 24 equals 58.
Victoria used a hundred square to add two tens and four ones to number 34. Two tens and four ones makes 24. The missing number in the addition sentence was number 24. 34 plus 24 equals 58.