300 + 100 + 50 + 50 + 90 + 10 + 400 + 1000
= 300 + 100 + ( 50 + 50 ) + ( 90 + 10 ) + 400 + 1000
= 300 + 100 + 100 + ( 90 + 10 ) + 400 + 1000
= 300 + 100 + 100 + 100 + 400 + 1000
= 300 + 100 x 3 + 400 + 1000
= 300 + 300 + 400 + 1000
= 600 + 400 + 1000
= 1000 + 1000
= 2000
300 + 100 + 50 + 50 + 90 + 10 + 400 + 100
= 300 + 100 + ( 50 + 50 ) + ( 90 + 10 ) + 400 + 1000
= 400 + 100 + 100 + 400 + 1000
= ( 400 + 100 + 100 + 400 ) + 1000
= 1000 + 1000
= 2000
kick cho mình nha