Seeking documents: skillfully calculating 72 + 73 + 74 + 75 + 76 + 77 + 78
This is an arithmetic sequence summation, you can pair, 72 and 78 add is equivalent to two 75 add, an analogy. So, sum is equal to 75 * 7 = 525
This is an arithmetic sequence summation, you can pair, 72 and 78 add is equivalent to two 75 add, an analogy. So, sum is equal to 75 * 7 = 525