# Triangular Numbers using LMC A triangular number correspond to the number of dots that would appear in an equilateral triangle when using a basic triangular pattern to build the triangule.

The triangular numbers sequence contains all the triangular numbers in order.

The first 10 numbers of the triangular number sequence are:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, … The following table shows how we can calculate each triangular number from this sequence:

 Triangular Number Calculation 1 =1 3 =1+2 6 =1+2+3 10 =1+2+3+4 15 =1+2+3+4+5 … …

#### Little Man Computer

Your challenge is to write a program using one of the following online LMC Simulators to calculate and output the first 10 triangular numbers of this sequence.

#### LMC Instruction Set

Note that in the following table “xx” refers to a memory address (aka mailbox) in the RAM. The online LMC simulator has 100 different mailboxes in the RAM ranging from 00 to 99.

 Mnemonic Name Description Op Code INP INPUT Retrieve user input and stores it in the accumulator. 901 OUT OUTPUT Output the value stored in the accumulator. 902 LDA LOAD Load the Accumulator with the contents of the memory address given. 5xx STA STORE Store the value in the Accumulator in the memory address given. 3xx ADD ADD Add the contents of the memory address to the Accumulator 1xx SUB SUBTRACT Subtract the contents of the memory address from the Accumulator 2xx BRP BRANCH IF POSITIVE Branch/Jump to the address given if the Accumulator is zero or positive. 8xx BRZ BRANCH IF ZERO Branch/Jump to the address given if the Accumulator is zero. 7xx BRA BRANCH ALWAYS Branch/Jump to the address given. 6xx HLT HALT Stop the code 000 DAT DATA LOCATION Used to associate a label to a free memory address. An optional value can also be used to be stored at the memory address.

#### Solution

The following Assembly/LMC code provides a good example of how branching (e.g BRP instruction) can be used to create a loop (iteration). #### Did you know?

In the code above, loop, counter, numbers, one and ten are called labels. ADD, OUT, STA, LDA, BRP, SUB, HLT, DAT are the mnemonics, each of them representing the opcode of an instruction.

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