Investing in the stock market is an exercise in numbers.

There are fundamental numbers and technical indicators, not to mention stock prices, volume and other indicators.

Then there is the economy, which produces a blizzard of its own numbers.

But which economic numbers are really important and which not so much?

Two of the numbers you should keep an eye on are interest rates and employment.

Interest rates change daily in response to market conditions.

However, big changes (or at least changes that have a big impact) happen when the Federal Reserve's Open Market Committee meets.

The committee has eight scheduled meetings each year.

The Fed influences short term rates and their actions can have a major and immediate influence on the market.

Even when the Fed doesn't change anything its comments on the state of the economy and future interest rates are closely watched.

If you are planning on buying or selling stocks and especially bonds, you will want to know where the Fed is on interest rates and if they are likely to change.

Employment numbers, which are announced weekly, can move the market in the short term, but their influence is greater over a longer period.

The reason is rising employment is good for the economy (not to mention those finding work).

Falling employment (or rising unemployment as it is often reported) is seen as a negative for long-term stock growth.

Consumer spending, which has a major influence on profits for many companies, falls when people are afraid of losing their job or are pessimistic about finding work.

Investors should watch employment trends and consider adjusting holdings to reflect rising or falling employment.