15/17-1/13

Let's calculate: $\frac{15}{17}-\frac{1}{13}$

ⓘ To add fractions, put them over the same denominator, then add the numerators. We choose $221$, the least common multiple of $17$ and $13$. Multiplying the numerator and the denominator by the same number does not change the fraction: $\frac{15}{17}-\frac{1}{13}$ = $\frac{15\times 13}{17\times 13}-\frac{1\times 17}{13\times 17}$ = $\frac{15\times 13-1\times 17}{17\times 13}$

$\frac{15\times 13-1\times 17}{17\times 13}$

ⓘ Multiplications are done before additions and subtractions: $15\times 13$ = $15\times (10+3)$ = $15\times 10+15\times 3$ = $150+45$ = $195$, $1\times 17$ = $17$

ⅰ $17\times 13$ = $17\times (10+3)$ = $17\times 10+17\times 3$ = $170+51$ = $221$

$\frac{195-17}{221}$

ⓘ Calculate the numerator and denominator before dividing: $195-17$ = $178$

▶Result:   $\frac{178}{221}$

The numeric value of: $\frac{178}{221}$ is:

▷ $\approx 0.8054$