Goi so hs khoi 6 la a . Ta co : a chia het cho 10,12,15 va 50 nho hon hoac =a ,100 lon hon hoac =a
Suy ra : a thuoc BC(10 , 12 ,15 )
10=2×5
12=2^2 × 3
15=3×5
BCNN(10,12,15)=2^2×3×5=60
BC(10,12,15)=B(60)={0;60;120;•••}
=>BC(10,12,15)={0;60;120;•••}
Vi 50 nho hon hoac =a 100 lon hon hoac =a
=>a=60
Vay so hoc sinh khoi 6 cua truong do la 60