Question

Calculati suma 1+3+5+7+......+97+99

Answer 1

Folosim formula: $1+3+5+7+...+n = (\frac{n+1}{2})^{2}$

$1+3+5+7...+97+99 = (\frac{99+1}{2})^{2} = (\frac{100}{2})^{2} = 50^{2} = 2500$