Question Video: Adding Two Numbers up to 99 Using a Hundredth Table Mathematics • 1st Grade

Video Transcript

There were nine boys at a park. Then 15 more boys came to the park to play. What is the total number of boys? Find the number by using the chart to count.

We know there were nine boys at the park. Then 15 more boys came to the park. We need to find nine plus 15 using the chart. We need to start counting at number nine, which has been circled already on the chart. And we need to count forward 15 places. We could count in ones. We could add 10.

The number underneath any given number on a hundred square is always 10 more. One plus 10 is 11. 11 plus 10 is 21. So nine plus 10 is 19. Now we have to add the five because 15 is 10 plus five. So let’s start counting at number 19 and move forward five places: one, two, three, four, five. Nine plus 15 equals 24. The total number of boys at the park is 24.