Steep Jump in Consumer Credit Seen : Indicators: Figure increased more rapidly in March than it has in seven months, despite evidence the economy is slowing.

Consumer credit increased more rapidly in March than it has in seven months, despite other evidence that the economy is slowing, the Federal Reserve Board said Friday.

Borrowing rose 17.9% at an annual rate in March, or $13.8 billion, the steepest increase since a jump of 21.3%, or $15.2 billion, in August. In February, credit rose 10%, or $7.7 billion.

Most signs have pointed to a dramatic slowdown in consumer spending this year after a booming expansion last year.

The surprisingly strong pickup in borrowing in March could be due to the growing habit among Americans of paying with plastic instead of cash for an increasing variety of goods, including groceries.

Consumer credit includes all household debt not secured by real estate, including home equity loans and home mortgages.

The use of revolving credit, including credit cards, increased 22.9% at an annual rate in March, compared to 22.0% in February. The latest advance totaled $6.7 billion, compared to $6.3 billion the previous month.

Automobile loans rose 9.8%, or $268 million, compared to an increase of 10.6%, or $287 billion, a month earlier.

The category that includes loans for mobile homes, education, boats, trailers and vacations climbed 21.3%, or $4.4 billion, contrasted with a decrease of 7.1%, or $1.5 billion, in February.

Overall, outstanding consumer credit rose to $941.8 billion from $928 billion. All figures are adjusted for seasonal variations.