Respuesta :
mental math and associative property of addition
i look at 173 and 427 and see that
73+27=100
i add now the 100(from 173)+400(from 427)+100(see above)=600
easy
600+301=901
i look at 173 and 427 and see that
73+27=100
i add now the 100(from 173)+400(from 427)+100(see above)=600
easy
600+301=901
Sum Using Associative property of addition
A+(B+C)=(A+B)+C=(A+C)+B
→301 + 173 + 427
=301 +(173+427)------Combining 173 and 427 first ,as adding unit digit of both three digit number gives 0.
=301 + 600
=901
⇒Using mental math
Add Hundreds=300+100+400
=800
Add tens=73+27
=100
Ones=1
Combine these three numbers
=800+100+1
=901