X=(49+7)+1x=56+1x=57
6 + 49 = 55
349
7(7 + 9)
Sum of numbers from 1 to 100:(1+100) + (2+99) + (3+98) + (4+97) + ... + (49+52) + (50+51) =50 pairs, each pair adds up to 101= (50 x 101)= 5,050
1 + 3 + 5 + ... + 49 = ((49 + 1)/2)2 = 625
the sum of 1 plus 9 is 10 because 1+9
1 + 4 + 16 + 25 + 36 + 49 = 131
0
51
81 + 1 + 1 + 1
4.9 + 1 = 5.9