# TCS Placement: Sample Questions 435 - 436 of 502

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## Question 435

### Question

MCQ▾Ray writes a two digit number. He sees that the number exceeds 4 times the sum of its digits by 3. If the number is increased by 18, the result is the same as the number formed by reversing the digits. Find the number.

### Choices

Choice (4) | |
---|---|

a. | 35 |

b. | 57 |

c. | 42 |

d. | 49 |

### Answer

a.### Explanation

Let the two digit number be xy.

The number exceeds 4 times the sum of its digits by 3.

If the number is increased by 18, the result is the same as the number formed by reversing the digits.

Solving equation (i) , we will get

Solving equation (ii) , we will get

Solving equation (iii) and (iv) , we will get x = 3 and y = 5

So, required number will be 35.

## Question 436

### Describe in Detail

Essay▾What are the notations used in evaluation of arithmetic expressions using prefix and postfix forms?

### Explanation

- Polish and Reverse Polish are the notations used in evaluation of arithmetic expressions using prefix and postfix forms.
- Polish notation:
- Polish notation also known as prefix notation is a form of notation for logic, arithmetic, and algebra, which places operators to the left of their operands.
- Prefixing the operator to the number is thus called Polish notation.
- For e. g. , Polish notation:+ 22

- Reverse polish notation:
- Reverse Polish notation (or RPN) is a mathematical notation in which every operator follows all of its operands (polish notation puts the operator in the prefix position) .
- Thus, suffixing the operator to the number is called reverse Polish notation.
- For e. g. , Reverse Polish notation: 22 +