Katy is very interested in cryogenics (the study of very low temperatures). With the help of her science teacher she is doing an experiment on the effect of low temperatures on bacteria. She cools one sample of bacteria to a temperature of -51 degrees Celsius and another to -76 degrees Celsius. What was the temperature difference in the two experiments?

1)

Answer:25

• How do you get the answer?-51 – (-76)

Keep – change – opposite-51 + 76 = 25

On Tuesday the mailman delivers 3 checks (money for you!) for $5 each and 2 bills (money you owe!) for $2 each. If you had a starting balance of $25, what is the ending balance?

2)

Answer is $36

How do you get this?25 +5 + 5 + 5 – 2 -2

An elevator is on the twentieth floor. It goes down 11 floors and then up 5 floors. What floor is the elevator on now?

3)

Answer is 14.

20 – 11 + 5

Joe is playing a game with a regular die. If the number that turns up is even, he will gain 5 times the number that comes up. If it is odd, he will lose 10 times the number that comes up. He tosses a 3. Express the results as an integer.

4)

Answer: -30

How do you get this?-10 x 3 = -30

It will be – 12º tonight. The weatherman predicts it will be 25º warmer by noon tomorrow. What will the temperature be by noon tomorrow?

5)

Answer:13°

Equation is:-12 + 25 = 13

A sprinkler was -8 feet below ground level. Mr. S has a machine that digs - 2 feet at a time. How many digs does he need to make in order to reach the sprinkler?

6)

Answer:

4 digs

Equation:-8/-4 = 2