Answer :
Sure! Let's go through each calculation and explain how you can do them mentally:
a. Calculating [tex]\(99 + 54\)[/tex]:
1. Think of 99 as 100 because it's easier to work with whole numbers.
2. Add 100 and 54, which gives you 154.
3. Since you added 1 extra when you rounded 99 up to 100, subtract 1 from 154.
4. The final answer is 153.
b. Calculating [tex]\(244 - 99\)[/tex]:
1. Round 99 up to 100 for easier subtraction.
2. Subtract 100 from 244, getting 144.
3. Now add back the 1 that you subtracted extra by rounding 99 up, so add 1 to 144.
4. The final answer is 145.
c. Calculating [tex]\(99 \times 6\)[/tex]:
1. Think of 99 as 100 - 1.
2. Multiply 100 by 6 to get 600.
3. Then multiply 1 by 6 to get 6, and subtract this from 600.
4. The final answer is 594.
d. Calculating [tex]\(99 \times 15\)[/tex]:
1. Again, consider 99 as 100 - 1.
2. Multiply 100 by 15 to get 1500.
3. Multiply 1 by 15 to get 15, and then subtract this from 1500.
4. The final answer is 1485.
By following these steps, you can perform each calculation mentally with ease!
a. Calculating [tex]\(99 + 54\)[/tex]:
1. Think of 99 as 100 because it's easier to work with whole numbers.
2. Add 100 and 54, which gives you 154.
3. Since you added 1 extra when you rounded 99 up to 100, subtract 1 from 154.
4. The final answer is 153.
b. Calculating [tex]\(244 - 99\)[/tex]:
1. Round 99 up to 100 for easier subtraction.
2. Subtract 100 from 244, getting 144.
3. Now add back the 1 that you subtracted extra by rounding 99 up, so add 1 to 144.
4. The final answer is 145.
c. Calculating [tex]\(99 \times 6\)[/tex]:
1. Think of 99 as 100 - 1.
2. Multiply 100 by 6 to get 600.
3. Then multiply 1 by 6 to get 6, and subtract this from 600.
4. The final answer is 594.
d. Calculating [tex]\(99 \times 15\)[/tex]:
1. Again, consider 99 as 100 - 1.
2. Multiply 100 by 15 to get 1500.
3. Multiply 1 by 15 to get 15, and then subtract this from 1500.
4. The final answer is 1485.
By following these steps, you can perform each calculation mentally with ease!
