Answer:
1987 + 1257 = 3247
Explanation:
We are going to use a base number to start from. That number is 1,987 where the thousand is 1, the hundred is 9 and the ten is 8.
Then we are going to add 1,257 which will be 3,247. Thus we will have a new thousand which is 3 (formerly 1), a new hundred which is 2 (formerly 9), and finally, a new ten which is 5 (formerly 7).
1987 + 1257 = 3247 gives you a new thousand, a new hundred and a new ten.