4. Adding or removing a bracket after “×”, no changes to the
“×” and “÷” sign in the bracket (No “+” and “–” sign in the
bracket )
38×25×6
= 19×2×25×2×3
= 19×(2×25×2)×3
= 19×100×3 = 5700
124×25
= 124×(100÷4)
= 124×100÷4
= 124÷4×100 = 3100
Also:
a×(b+c) = a×b+a×c
4.25×18
= (4 + 0.25)×18
= 4×18 + 0.25×18
= 72 + 18÷4
= 72 + 4.5 = 76.5
From the above example:
×0.25 ÷4
×0.5 ÷2
×0.125 ÷8
5. Adding or removing a bracket after “÷”, the sign in the
bracket will be changed; “×” becomes “÷” and
“÷” becomes “×” (No “+” and “–” sign in the bracket )
8.4÷5÷6
= 8.4÷(5×6)
= 8.4÷30 = 0.28
27000÷125
= 27000÷(1000÷8)
= 27000÷1000×8
= 27×8 = 216
From the above example:
÷ 0.25 ×4
÷ 0.5 ×2
÷ 0.125 ×8