Round off the following numbers to the nearest 10 and calculate the sums.

Here are the solutions to your mathematics exercises.

: Round off to the nearest 10.

1. To round 465 to the nearest 10, look at the ones digit. Since it is 5, round up the tens digit. $$465 \approx \boxed{470}$$
2. To round 8235 to the nearest 10, look at the ones digit. Since it is 5, round up the tens digit. $$8235 \approx \boxed{8240}$$
3. To round 1932 to the nearest 10, look at the ones digit. Since it is 2 (less than 5), keep the tens digit the same. $$1932 \approx \boxed{1930}$$
4. To round 89 to the nearest 10, look at the ones digit. Since it is 9 (greater than 5), round up the tens digit. $$89 \approx \boxed{90}$$
5. To round 4599 to the nearest 10, look at the ones digit. Since it is 9 (greater than 5), round up the tens digit. This means the 9 in the tens place becomes 10, so carry over to the hundreds place. $$4599 \approx \boxed{4600}$$

: Use any method to calculate the following.

1. $3572 + 2981 = \boxed{6553}$
2. $4175 + 3834 = \boxed{8009}$
3. $6715 + 285 = \boxed{7000}$
4. $1853 + 7146 = \boxed{8999}$
5. $4562 + 3825 = \boxed{8387}$
6. $6258 + 649 = \boxed{6907}$
7. $947 + 384 = \boxed{1331}$
8. $4705 + 2327 = \boxed{7032}$
9. $8376 + 4753 = \boxed{13129}$
10. $6482 + 7586 = \boxed{14068}$

: Replace the letters with the correct numbers.

In a number pyramid, each block is the sum of the two blocks directly below it.