# Deep Dive: Understanding math and substring formula for custom exports

Expensify Team, Expensify Student Ambassador Posts: 241 Expensify Team
edited August 2021

## The more you know - - -

Information about the current user exporting the reports.  This is useful if you need to print the name of the exporter.

• To export the email of the currently logged in Expensify user -
• {user:email} would output [email protected] assuming that is the currently logged in Expensify user's email.
• {user:email|frontPart} would output bob assuming that is the currently logged in Expensify user's email.
• You are able to add formulas that are a math type, allowing you to do arbitrary mathematical equations in your export.
• * — Multiplication {math: 3 * 4} output 12
• / — Division {math: 3 / 4 }output 0.75
• + — Addition {math: 3 + 4 }output
• - — Subtraction {math: 3 - 4 }output -1
• ^ — Exponent {math: 3 ^ 4 } output 81
• sqrt — The square root of a number. {sqrt:64} output 8

• Note - You can also combine the value of any two numerical fields. For example, you can use {math: {expense:tag:glcode} + {expense:category:glcode}} to add the value of the Tag GL code with the Category GL code.
• Substring formulas will output a subset of the string in question. It is important to remember that the count starts at 0 not 1.
• `<strong>{expense:merchant|substr:0:4}</strong>` would output `Star` for a merchant named Starbucks. This is because we are telling it to start at position 0 and be of 4 character length.
• `<strong>{expense:merchant|substr:4:5}</strong>` would output `bucks` for a merchant named Starbucks. This is because we are telling it to start at position 4 and be of 5 character length.
Related articles
Have a question or want to know more? Start a discussion here!
Tagged: