How to simplify the calculation of 41x101? How about (0.18 + 0.9) + 9? And 907x99 + 907... 2.5x0.87x40? What about these?

How to simplify the calculation of 41x101? How about (0.18 + 0.9) + 9? And 907x99 + 907... 2.5x0.87x40? What about these?

41x(100+1)=4100+41=4141
(0.18 + 0.9) + 9 = 1.08 + 9 = 10.08
907x99+907=907x(99+1)=90700
2.5x0.87x40=2.5×40×0.87=100×0.87=87

How to calculate 847-578 + 398-222 simply

847-578+398-222
=(800+47)+(400-2)-(578+222)
=800+47+400-2-800
=47-2+400
=45+400
=445

1300 △ 25 = simple calculation

1300÷25
=13*(100÷25)
=13*4
=52

How to calculate 298-188 simply

298-200+18
98+18
one hundred and sixteen