2/17-12/13

Let's calculate: $\frac{2}{17}-\frac{12}{13}$

ⓘ Add fractions by using a common denominator and then adding their 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: $\frac{2}{17}-\frac{12}{13}$ = $\frac{2\times 13}{17\times 13}-\frac{12\times 17}{13\times 17}$ = $\frac{2\times 13-12\times 17}{17\times 13}$

$\frac{2\times 13-12\times 17}{17\times 13}$

ⓘ Multiplications are done before additions and subtractions: $2\times 13$ = $2\times (10+3)$ = $2\times 10+2\times 3$ = $20+6$ = $26$, $12\times 17$ = $(10+2)\times 17$ = $10\times 17+2\times 17$ = $170+34$ = $204$

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

$\frac{26-204}{221}$

ⓘ Calculate the numerator and denominator before dividing: $26-204$ = $-178$

▶Result:   $-\frac{178}{221}$

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

▷ $\approx -0.8054$