Complete the following: 50 plus 20 plus four equals what plus what, which equals what?
First, we need to calculate 50 plus 20 plus four. We can use a place value grid to help us add these three numbers. Our first number is 50. Then we have to add 20 and four. How many ones do we have altogether? Zero plus zero plus four equals four. How many tens do we have altogether? Five tens plus two tens makes a total of seven tens. 50 plus 20 plus four equals 74.
The next part of our question asks us which two numbers we can add together to total 74, or which two numbers are equal to 50 plus 20 plus four. We could partition 74 into its tens and ones. We know that 74 has four ones and seven tens, which is worth 70. So 50 plus 20 plus four is equal to 70 plus four. And we know that 70 plus four equals 74.
The missing numbers in the equation are 70, four, and 74. 50 plus 20 plus four is equal to 70 plus four, which equals 74. We used a place value grid to help us add the first three numbers in columns. Then we partitioned the answer to find the three missing numbers.