Questions related to determination of unit digit for all competitive examination(SSC CGL BANK RAIL TET all world Math competition)
For any competitive examination concept of mathematics is too important. Importance of mathematics is constantly getting the center stage in today’s competitive environment. Mathematics , thus forms an integral part of the competitive examination and it can be hard nut to crack if the students are not familiar with the knowledge of the subject.Series problems for competitive exam(Mathematics)
Concept of Units Digit
- If a number whose last digit is 5, is multiplied by an odd number, the unit digit of the product will always be 5
- If a number whose last digit is 5 , is multiplied by an even number , the unit digit of the product is always zero,
- The unit digit follows a periodic pattern that is after a particular period it repeats in a cyclic form.
- The unit digit of 0,1,5,6 is always the same irrespective of their powers raised on them.
- The last digit of 4 and 9 follows the pattern of odd even i.e., their period is 2
Now some important questions related to determination of Unit Digit
- What will be the unit digit in 7105 ? (SSC 2005) Ans- 7
- The digit in the units place of the product (2464)1793 X (615)317X (131)491 (SSC 2004) Ans – 0
- The digit in the units place of (251)98 + (21)29 –(106)100 +(705)35 –(16)4 +259 (SSC 2000) Ans- 4
4. The last digit of (1001)2008 + 1002 is ? (SSC 2011) Ans -3
5. The digit in unit place of the product 81x82x83x………….x89 is ? (SSC 2003) Ans- 0