1. Calculează:
a) 10 000 - 108 x 23 +225 : 5 =
1011 + 110:10 - 101 x 1-1 =
873 x 15 x 3 x 0 + 425:5: 5 =
3099 - 450 : 90 + 9 307 - 93 =
331 x 45 - 784:7 + 100 : 100 =
15 930 – 7 880: 2- 78 000 : 1 000
749:7 + 309 : 3 + 70 x 9 =
b) 197 825:25 – 7 900 + (100 – 9 x 9) – 31 =​