Create, Modify & Test

Example

# Create a variable called example and set it to 2
:var example .= 2
# Add 1 to example
:var example += 1
# Subtract 2 from example
:var example -= 2
# Set example to 1
:var example = 1
# Say something if example is 1
execute if :tvar example matches 1 run say Variable example is equal to 1!

Compiled

scoreboard objectives add example dummy
scoreboard players set --databind example 2
scoreboard players add --databind example 1
scoreboard players remove --databind example 2
scoreboard players set --databind example 1
execute if score --databind example matches 1 run say Variable example is equal to 1!