замени сумму произведениями: 100×5+100×0=,100×4+50×4+50×4+9×4=,400×2+90×2+9×2=,60×8+60×4=,5×40+2×40=,200×1+200×2=?

100·5+100·0 = 100·(5+0) = 100·5 = 500

100·4+50·4+50·4+9·4 = 4·(100+50+50+9) = 4·209 = 836

400·0+90·2+9·2 = 2·(400+90+9) = 2·499 = 998

60·8+60·4 = 60·(8+4) = 60·12 = 720

5·40+2·40 = 40·(5+2) = 40·7 = 280

200·1+200·2 = 200·(1+2) = 200·3 = 600