Question

Sum of numbers between 4 and 100?

Answer 1

add from \(1\) to \(100\) and then subtract \(1+2+3=6\)

Answer 2

\[SUM = \frac{ n(a_1 + a_n) }{ 2 }\]

n is the number of terms (96). a1 is the first term (4) and an is the last term (100)

Answer 3

Simple trick\[\begin{array}{}
S &=& 4&+&5&+&...&+&99&+&100 \\
S &=&100 &+& 99 &+& ... &+& 5 &+ &4 \\
S+S &=&104 &+& 104 &+&... &+& 104 &+&104 \\
2S& =& 97 \times 104
\end{array}\]

Answer 4

my mistake. 97 terms :)

Answer 5

my mistake. 97 terms :)