i need help with this math

Answer:
9870
Step-by-step explanation:
There are 140 numbers so there are 70 pairs of numbers
The sum of each pair taking them from the ends is 1+140 = 141
(2+139) = 141 and (3+138 = 141) and so on
70 * 141 = 9870
The sum of all the number is 9870