1. Decimal → 0,1,2,3,4,5,6,7,8,9,10,……
2. Octal → 0,1,2,3,4,5,6,7,8,10,11,12,13,14,15,16,17,…………
3. Hecta → 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,……………

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1. Decimal to any base (b)→ keep dividing by base (b) , take reminder and write in opposite
2. Convert any base (b) to decimal → multiply and add the power of base (b) with digits