I need help with this:
Find the sum
5 + 10 + 15 + ... + 295 + 300
2006-09-11 07:49:21 · 6 answers · asked by Ryan H 2 in Science & Mathematics ➔ Mathematics
= 5(1 + 2 + ... + 100)
= 5(100*101/2)
= 25250
2006-09-11 07:52:04 · answer #1 · answered by bensonlee5 1 · 0⤊ 0⤋
In an algebraic solver it would be the sum from 1 to 60 of 5*n, where n is an integer. To do it by hand, you use the formula
n*(n+1)/2 = the sum of all the integers from 1 to n
then multiply that by 5 (since your sum is all multiples of 5)
this is 5*60*61/2 =
9150
2006-09-11 15:01:33 · answer #2 · answered by bordag 3 · 0⤊ 0⤋
sum = 5 (1+2+3+.....60)
1+2+3+......+58+59+60
pair 1 and 60 =61
pair 2 and 59 = 61
pair 3 and 58 = 61
how many pairs of 61......???
from 1 to 60 we have 60 numbers => 30 pairs
so 1+2+3+....+60 = 61*30
the sum is 5*61*30
2006-09-11 14:55:41 · answer #3 · answered by Anonymous · 0⤊ 0⤋
5 * (1+2+3+4....+60)
1+2+3+4+....+60 = 60*61/2 = 1830
1830*5 = 9150
2006-09-11 14:53:08 · answer #4 · answered by bob h 3 · 0⤊ 0⤋
5(1+2+3+4+.........................................+60)
sum of n natural nos=n(n+1)/2=60*61/2
=1830
so 5+10+15+...............+295+300
=5*1830=9150
2006-09-11 14:53:31 · answer #5 · answered by raj 7 · 0⤊ 0⤋
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=9150
2006-09-11 14:54:13 · answer #6 · answered by Scott S 4 · 0⤊ 0⤋