Question

Write a MARIE program to sum the numbers 1 + 2 + 3 + 4 + … + N, where the user enters N.

Answer 1

Answer:

The formula for calculating sum of consecutive N numbers = (N(N+1))/2

Explanation:

Algorithm:

• Taking N as the input, increment it to obtain N+1.

• Multiply N with N+1.

• Divide the obtained product obtained by 2.

Steps:

• Load the data from the memory location (301BH, random choice) into the accumulator

• Move the data into B

• Increment the value in the accumulator by one and move it to the register C

• Initialize the accumulator with 0

• Multiplication step: Keep adding B to accumulator. The B has to be added equal number of times as the value of C

• Initialize B with 00H. B will store the quotient of the division

• Initialize C with 02H. This is the divisor for the division

• Division step: Keep subtracting C from A till A becomes 0. For each subtraction, increment B by one

• The final answer is in B. Move it to A. Then store the value of A in 301CH (again random choice)

Program:

LDA 301BH      

MOV B, A

INR A

MOV C, A

MVI A, 00H

LOOP1 ADD B

DCR C

JNZ LOOP1

MVI C, 02H

MVI B, 00H

LOOP2 INR B

SUB C

JNZ LOOP2

MOV A, B

STA 301CH

HLT

The output will be stored in 302CH