800-400= 1400-200= 300+600= 800-50= 400+300=

1000-400= 300+500= 900-650= 500+900= 900-700=

300-200= 200+500= 400+300= 1400-300= 400+300=

500+300= 300+ 1200= 900- 100= 400+300= 200- 100=

200+3 100= 1300- 100= 1700+200= 500- 100= 300+400=

1000-300= 200+300= 200- 100= 300+500= 800-200=

200+300= 700-250= 300- 100= 400+500= 400- 100=

2, with vertical calculation

8 10-466= 445-277= 356+626= 865-578= 445+385=

1000-455= 345+543= 957-679= 53 1+975= 987-799=

342-274= 258+553= 445+369= 468-389= 457+368=

597+324= 385+247= 978- 199= 467+333= 258- 168=

275+345= 300- 1 10= 170+244= 520- 155= 369+470=

1000-333= 246+357= 270- 144= 356+543= 820-278=

285+369= 700-264= 378- 197= 485+522= 474- 179=

3, vertical calculation and checking calculation.

468-357= 569-367= 358+53 1=

Check calculation: Check calculation:

785-436= 579-436= 258+648=

Check calculation: Check calculation:

467-358= 258- 138= 653+259=

Check calculation: Check calculation:

368-233= 136+845= 357+458=

Check calculation: Check calculation: