Question

Find the sum of all 2 digit multiples of 8 .

Answer 1

Step-by-step explanation:

Solution:-

First the 2digit multiples of 8 are=16,24,32......96

• They are clearly in a AP

Where

a=16

l=96

Common difference=(d)=24-16=8

• We need to find the sum
• Let's use formula of AP

${\boxed{S{}_n={\dfrac {n}{2}}(a+l)}}$

• Substitute the values

${:}\longmapset$${\dfrac {12}{2}}(16+96)$

${:}\longmapset$$6×(112)$

${:}\longmapset$${\underline{\boxed{\bf {S_n=696 }}}}$