How to differentiate between decimal and larger number, in countries that use a comma

This might be off-topic here, since most people speaking English write decimals with a period and not a comma, but I'm unsure where else to ask this. Let me know, if you know of a better place to ask or where to research this and I will remove my question.

How do people in countries that use commas as a decimal mark tell the difference between a decimal and a larger value?

For example, in the U.S., it's easy to tell the difference between 1.567 and 1,567. How would you tell the difference, in a country where they write their decimals like 1,567?

• They probably use a different convention for grouping numbers in threes, for example a space: From Wikipedia ('decimal point'): "The 22nd General Conference on Weights and Measures declared in 2003 that 'the symbol for the decimal marker shall be either the point on the line or the comma on the line'. It further reaffirmed that 'numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups' e.g. 1 000 000 000." – GoldenGremlin Jun 1 '16 at 14:06
• No country I'm aware of uses commas for both the decimal point and the thousands separator (or more generally digit group delimiter). If a country uses the comma as a decimal point, they'll invariably use something else for the thousands separator (delimiter). What they use instead may vary; but more and more frequently I'm seeing the simple space used as a thousands separator (some programming languages I know even emulate this by permitting underscores in numeric literals, like `1_000_000`). – Dan Bron Jun 1 '16 at 14:07