Question

s=4+8+12+...+152..
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Answer 1

$s = 4 + 8 +1 2 + ... + 152 \\ s = 4(1 + 2 + 3 + ... + 38) \\ s = \not4 _{ {}^{ \: 2} } \times \frac{38(38 + 1)}{\not2_{ {}^{ \: \: 1} } } \\ \\ s = 2 \times 38 \times 39 \\ s = 76 \times 39 \\ s = 2.964$