4*n(n+1)
.....5 .....Σ 9r ...r=1
It is 751500.Here's the first ten.6, 12, 18, 24, 30, 36, 42, 48, 54, 60
1422, 1431, 1440
They are infinitely many and they form an increasing sequence the sum is infinite.
No. Odd numbers can be written as the sum of consecutive integers, but some multiples of odd numbers are even.
The sum of the first 10 multiples of 3 is 165.
x = 22
The sum of the first 25 numbers is 25*26/2 = 325 So the sum of the first 25 multiples of 12 is 325*12 = 3900
Sum of the first 15 positive integers is 15*(15+1)/2 = 120 Sum of the first 15 multiples of 8 is 8*120 = 960
3(y+7)
" 3x + 5 " does.
90
975
75
5 + 10+15+20=50 ans
10 + 3x
4(x + 5)