Recent content by Sabeel

$-12\times10^{15}+61\times10^{14}=-12\times10\times10^{14}=10^{14}(-120+61)=-59\times10^{14}$ $3\times10^{9}-36\times10^{8}=3\times10\times10^{8}-36\times10^{8}=10^8 (30-36)=-6\times10^{8}=-60\times10^{7}$ Your hint was more than useful. Thank you so much.

Thank you for welcoming me, and thank you for your answer. Your hint is useful: $12^{21} - 10^{22} = 12^{21} -10\times 10^{21} =(12-10)10^{21}=2\times10^{21}$ I'll struggle with the others and report back.

Initially the expression A has 8 terms. So how is it reduced in the second line to 5 terms? Could you show me, please? Thank you. \begin{align*} A&=10^{28} -10^{22} +61\times10^{14}+12\times10^{21}-12\times10^{15}+3\times10^{9}-36\times10^{8}+9\times10^{2}\\ &=10^{28}...