n: \(=1256-\left\{256:8+25+216\right\}\)
=1256-32-25-216
=983
o: \(=500-\dfrac{\left\{5\cdot\left[409-3^2\right]+1000\right\}}{15}\)
\(=5000-\dfrac{5\cdot400+1000}{15}=5000-600=4400\)
p: \(=3^3-\left[157-9^2\right]:4\)
=27-19
=8
q: \(=24:\left\{390:\left[500-125-245\right]\right\}\)
\(=\dfrac{24}{390:130}=\dfrac{24}{3}=8\)
r: \(=1256-256:8-144:24-216\)
=1002