213 = 2.10² + 1.10¹ + 3.10⁰

421 = 4.10² + 2.10¹ + 1.10⁰

2009 = 2.10³ + 0.10² + 0.10¹ + 9.10⁰

abc = a.10² + b.10¹ + c.10⁰

abcde = a.10⁴ + b.10³ + c.10² + d.10¹ + e.10⁰

\(213=2×10^2+1×10^1+3×10^0\)

\(421=4×10^2+2×10^1+1×10^0\)

\(2009=2×10^3+0×10^2+0×10^1+9×10^0\)

abc=a×10^2+b×10^1+c×10^0

abcde=a×10^4+b×10^3+c×10^2+d×10^1+e×10^0

\(213=200+10+3=2\cdot100+10+3=2\cdot10^2+10^1+3\)

\(421=400+20+1=4\cdot100+2\cdot10+1=4\cdot10^2+2\cdot10^1+1\)

\(2009=2000+9=2\cdot1000+9=2\cdot10^3+9\)

\(abc=a\cdot100+b\cdot10+c=a\cdot10^2+b\cdot10^1+c\)

\(abcde=a\cdot10000+b\cdot1000+c\cdot100+d\cdot10+e=a\cdot10^4+b\cdot10^3+c\cdot10^2+d\cdot10^1+e\)

a﴿ 213 = 200 + 10 + 3 = 2.100 + 10 + 3 = 2.10 ² + 10 ¹ + 3

b﴿ 421 = 400 + 20 + 1 = 4.100 + 2.10 + 1 = 4.10 ²+ 2.10 ¹ + 1

c﴿ 2009 = 2000 + 9 = 2 . 1000 + 9 = 2.10 ³ + 9

d﴿ abc = a.100 + b.10 + c = a.10 ² + b.10 ¹ + c

e﴿ abcde = a.10000 + b.1000 + c.100 + d.10 + e = a.10 ⁴+ b.10 ³+ c.10 ²+ d.10 ¹ + e

\(213=100+100+10+3=10^2+10^2+10^1+3\)

\(421=100+100+100+100+10+10+1=10^2+10^2+10^2+10^2+10^1+10^1+1\)\(2009=1000+1000+9=10^3+10^3+9\)

\(abc=10^2a+10^1b+c\)

\(abcde=10^4a+10^3b+10^2c+10^1d+e\)

895 = 8.100 + 9.10 + 5.1 = 8. 102 + 9.101 + 5.100

abc= a.100 + b.10 + c.1 = a. 102 + b.101 + c.100

Đề kiểu gì ấy chả hiểu quái gì cả chán 

987 = 10² . 9 + 10 .8 + 10⁰ .7

2564 = 10³ . 2 + 10² . 5 + 10 . 6 + 10⁰ . 4

abcde = 10⁴ . a + 10³ .b + 10² . c + 10.d + 10⁰. e

987= 9.100+8.10+7.1

2564= 2.1000+5.100+6.10+4.1

abcde (abcde có gạch ở trên)= a.10000+b.1000+c.100+d.10+e.1

987 = 9 . 10² + 8 . 10 + 7;

2564 = 2 . 10³ + 5 . 10² + 6 . 10 + 4;

abcde = a . 10⁴ + b . 10³ + c . 10² + d . 10 + e

987 = 9 . 10² + 8 . 10 + 7;

2564 = 2 . 10³ + 5 . 10² + 6 . 10 + 4;

abcde = a . 10⁴ + b . 10³ + c . 10² + d . 10 + e

987 = 9 . 10² + 8 . 10¹ + 7 . 10⁰

2564 =2 . 10³ + 5 . 10² + 6 . 10¹ + 4 . 10⁰

abcde = a . 10⁴ + b . 10³ + c . 10² + d . 10¹ + e . 10⁰

987=9.100+8.10+7.1=9.10²+8.10+7.10⁰

2564=2.1000+5.100+6.10+4.1=2.10³+5.10²+6.10+4.10⁰

abcde=a.10000+b.1000+c.100+d.10+e.1=a.10⁴+b.10³+c.10²+d.10+e.10⁰

987=900+80+7=9.100+8.10+7.1=9.10²+8.10¹+7.10⁰

2564=2000+500+60+4=2.1000+5.100+6.10+4.1=2.10³+5.10²+6.10¹+4.10⁰

abcde=10000.a+1000.b+100.c+10.d+1.e=10⁴.a+10³.b+10².c+10¹.d+10⁰.e

987 = 9 x 100 + 8 x 10 + 7 x 1 = 9 x 10² + 8 x 10 + 7 x 10⁰

2564 = 2 x 1000 + 5 x 1000 + 6 x 10 + 4 x 1 = 2 x 10³ + 5 x 10² + 6 x 10 + 4 x 10⁰

abcde = a x 100000 + b x 1000 + c x 100 + d x 10 + e x 1x e = 10⁴ x a + 10³ x b + 10² x c + 10¹ x d + 10⁰ x e

987=9.10²+8.10¹+7.10⁰

^{2564=2.10^3+5.10^2+6.10^1+4.10^0}

^{abcde=a.10^4+b.10^3+c.10^2+d.10^1+e.10^0}

^{k mik nha}