Question

what is the sum of the first 100 even numbers

Answer 1

dorema, the sum,

2 + 4 + 6 + ... + 98 + 100

is an arithmetic series (i.e. the difference between consecutive terms is constant (here, it's 2)). You will have 50 terms in this series, your first term will be 2 (sometimes 0, but that won't change the sum), and your last will be 100. The formula for such a sum is\[s_n=\frac{n}{2}(a+l)\]where n is the number of terms, a is the first and l is the last (there's also another useful version which you can look up).

Your sum is then\[s_{50}=\frac{50}{2}(2+100)=25 \times 102 = 2550\]

Answer 2

thanks that was a BIG HELP!

Answer 3

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