How many two digit natural number is divisible by 7?

1.	How many two digit natural number is divisible by 7?
Answer» Two digit numbers which are divisible by 7 are 14,21,28,.....98.It forms an A.P.{tex}a = 14, d = 7, a_n = 98{/tex}{tex}a_n = a + (n - 1)d{/tex}{tex}98 = 14 + (n - 1)7{/tex}{tex}98 -14 = 7n - 7{/tex}{tex}84 + 7 = 7n{/tex}or, {tex}7n = 91{/tex}or, {tex}n = 13{/tex}

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