Question

find the sum of all off numbers from 1 to 150 . complete the activity​

Answer 1

to find :-

• the sum of all numbers from 1 to 150 .

we have :-

• a = 1
• l = 150

where,

• a = first term
• l = last term

Formula used :-

$\\ \\ \\ \tt s_n = \frac{n}{2} \big(a + l \big)$

Solution :-

$\\ \\ \\ \tt \: s_n \: = \frac{150}{2} \big(1 + 150 \big) \\ \\ \tt \:s_n \: = 75 \times 151 \\ \\ \tt \: s_n \: = 11325$

so, sum of all numbers from 1 to 150 is 11325 .

$\\ \\ \\ \bf \: other \: formula \: : - \\ \\ \\ \tt \: s_n \: = \frac{n}{2} \bigg(2a + ( n- 1) \bigg)$