A veterinary assistant must inventory all supplies each month. She counts the following number of thermometers: 4, 12, 7, 23, and 9. What is the total number of thermometers?

A veterinary assistant must inventory all supplies each month. She counts the following number of thermometers: 4, 12, 7, 23, and 9. What is the total number of thermometers?

• A. 45 thermometers
• B. 60 thermometers
• C. 50 thermometers
• D. 55 thermometers

Answer: (D)

Adding up several numbers to get a total is the skill being used here. To inventory the thermometers, sum all the counts: 4, 12, 7, 23, and 9. One way to do it cleanly is to group and add: 23 plus 12 equals 35, and 9 plus 4 equals 13. Then add those results together: 35 plus 13 equals 48, and finally add the remaining 7 to get 55. Another quick check is to add all at once: 4 + 12 + 7 + 23 + 9 also equals 55. So the total number of thermometers is 55.

Adding up several numbers to get a total is the skill being used here. To inventory the thermometers, sum all the counts: 4, 12, 7, 23, and 9.

One way to do it cleanly is to group and add: 23 plus 12 equals 35, and 9 plus 4 equals 13. Then add those results together: 35 plus 13 equals 48, and finally add the remaining 7 to get 55. Another quick check is to add all at once: 4 + 12 + 7 + 23 + 9 also equals 55.

So the total number of thermometers is 55.