The number of job openings increased to 6.6 million on the last business day of March, the U.S. Bureau of Labor Statistics reported Tuesday.

Over the month, hires and separations were little changed at 5.4 million and 5.3 million, respectively. Within separations, the quits rate was little changed at 2.3 percent and the layoffs and discharges rate was unchanged at 1.1 percent.

The release included estimates of the number and rate of job openings, hires, and separations for the nonfarm sector by industry and by four geographic regions.

Large numbers of hires and separations occur every month throughout the business cycle.

Net employment change results from the relationship between hires and separations. When the number of hires exceeds the number of separations, employment rises, even if the hires level is steady or declining.

Conversely, when the number of hires is less than the number of separations, employment declines, even if the hires level is steady or rising.

Over the 12 months ending in March, hires totaled 65.7 million and separations totaled 63.4 million, yielding a net employment gain of 2.3 million. These totals include workers who may have been hired and separated more than once during the year.