In a school, there are 812 students in the first two grades and twice this number in the other grades. How many students are in the school?
We’ve been told there are 812 students in the first two grades and twice this number — in the problem, when we see “this number”, it’s referring to the 812 students. So twice this number means twice the 812 students. And we know that twice means multiplied by two. Two times 812 are in all the other grades. To find the amount of students in the school, we’ll need to know the amount of students in the first two grades, and then add the amount of students in all the other grades.
Our first step will be to take the 812 students in the first two grades and multiply that by two to find out how many students are in all the other grades. Multiplying 812 times two, two times two is four, two times one is two, and two times eight is 16. 812 times two is 1624. We could also say 812 plus 812. If we break up the 800 and the 12 pieces, we know that eight plus eight equals 16. And so, 800 plus 800 equals 1600. And 12 plus 12 equals 24. 1600 plus 24 equals 1624.
To find our final answer, we’ll take the number of students in the first two grades, 812, and add that two 1624. Which is the number of students in all other grades. We start by adding in the ones place. Two plus four is six. One plus two, in the tens place, is three. In the hundreds place, we have eight plus six, which is 14. So we write down our four and carry over our one into the thousands place. In the thousands place, we have one plus one, which is two. And so, we can say there were 2436 students in the whole school.