Estimate Sums

Alice and her mom are cooking a healthy dinner together. They are preparing rice, turkey, and a salad! Let’s help them make their healthy dinner.

Here is the rice that Alice’s mom made. Alice will add 52 peas and 27 pieces of broccoli. Yum! About how many peas and pieces of broccoli did Alice add?

Hmmm, 52+27 is a little tricky to add together. If we round each of these addends to the nearest ten, adding them together will be much easier! This is called estimating the sum. Let’s try it!

Here is a number line with benchmark numbers in multiples of ten. Now let’s put 52 and 27 on the number line. Do you see the benchmark numbers closest to 52 and 27? That’s right! 50 is closest to 52 and 30 is closest to 27. We can easily add 50 and 30: 50+30=80. Alice put about 80 peas and broccoli pieces in the rice.

Let’s see if our estimated sum was correct. We can check our answer by adding 52 and 27! 2 plus 7 is 9 and 5 plus 2 is 7. That means 52 plus 27 equals 79. 79 is very close to 80. Great job!

Alice’s mom just took this turkey out of the oven. Yum! Alice will place 22 pieces of kale and 17 orange slices around the turkey. Can you help Alice find about how many pieces of kale and orange slices are around the turkey? Let’s use estimation to help!

Here are 22 and 16 on the number line. Notice that our benchmark numbers are still in multiples of ten. That is because we will round to the nearest ten. What benchmark numbers are closest to 22 and 16. Wow, 20! 22 rounded to the nearest ten is 20 and 16 rounded to the nearest ten is 20 as well. 20 and 20 are easy to add together: 20+20=40. That means Alice put about 40 pieces of kale and orange slices around the turkey.

Can you help Alice check her estimated sum? Let’s add 22 and 16. 2 plus 6 is 8 and 2 plus 1 is 3. That means 22 plus 16 equals 38. 38 and 40 are very close. Great job!

The last dish Alice will help her mom finish is this big, green salad. Alice will toss 74 olives and 24 tomato wedges in the salad. Let’s help Alice use estimation to find out about how many olives and tomato wedges are in the salad.

Here are 74 and 24 on the number line. Do you see the benchmark numbers closest to 74 and 24? That’s right! 74 rounded to the nearest ten is 70 and 24 rounded to the nearest ten is 20.

We know that 70+20=90, so Alice put about 90 olives and tomato wedges in the salad.

In order to check our answer, we can add 74 and 24 together. 4 plus 4 is 8 and 7 plus 2 is 9.

74+24=98. 98 and 90 are very close to each other, so our answer must be correct. Great job!

Thank you for helping Alice estimate sums today by rounding to the nearest ten. Now Alice and her mom can enjoy their healthy dinner!